For robust grasping of workpieces with complex surface geometries such as the plugs of electrical connectors (ECs), individually designed gripper jaws are commonly required. The manual design of the latter is time-consuming, iterative, expensive, and requires expert knowledge. Therefore, automating the design process offers the potential to increase efficiency and reduce costs. However, the plugs of ECs often involve interference contours which pose a high risk for a grasp to fail. Thus, this paper introduces an approach for the automated design of gripper jaws that considers complex surface geometries with interference contours. Thereby, expected geometric uncertainties in the relative pose between a plug and a gripper system can be parameterized by a user. The key steps of our approach are to automatically simulate collision volumes between the gripper jaws and the workpiece to map geometric uncertainties in software for computer-aided design (CAD) and to adapt the gripper jaws accordingly within minutes and without manual design. The results of the experimental validation using three different high-voltage plugs show that the presented approach is suitable for robust grasping of such workpieces. In summary, our work intends to contribute to a more efficient design process of gripper systems for workpieces with complex surface geometries such as plugs of ECs.